Albert Barnes Commentary Job 21:29

"Have ye not asked wayfaring men? And do ye not know their evidences," — Job 21:29 (ASV)

Have you not asked them that go by the way? – Travelers, who have passed into other countries, and who have had an opportunity of making observations, and of learning the opinions of those residing there. The idea of Job is that they might have learned from such travelers that such people were “reserved” for future destruction, and that calamity did not immediately overtake them.

Information was obtained in ancient times by careful observation and by traveling, and those who had gone into other countries would be highly regarded concerning a point like this. They could speak of what they had observed of the actual dealings of God there, and of the sentiments of sages there. The idea is that “they” would confirm the truth of what Job had said: that the wicked were often prosperous and happy.

And do you not know their tokens? – The signs, or intimations which they have given of the actual state of things in other countries, perhaps by the inscriptions, records, and proverbs, by which they had “signified” the result of their inquiries.